2.
Meanwhile, in a large bowl, using an electric mixer, beat 1 cup butter and raspberry jam on medium-high until smooth. Add marshmallow topping and confectioners' sugar and beat until fluffy and smooth, 3 minutes. Transfer mixture to a quart-size zip-top bag; with scissors, snip a small hole in one corner. Pipe frosting onto cooled cupcakes and serve immediately. (Store unfrosted cupcakes, in an airtight container, at room temperature, up to 2 days.)